chown

Change file owner and/or group.

Syntax
chown [-fhv] [-R [-H | -L | -P]] owner[:group]file ...
chown [-fhv] [-R [-H | -L | -P]] :groupfile ...
Options
-R Recurse: Change the mode of file hierarchies rooted in the files
instead of just the files themselves.
-R -H Follow symbolic links on the command line
(by default Symbolic links within the tree are not followed.)
-R -L All symbolic links are followed.
-R -P No symbolic links are followed. (default)
-f Do not display a diagnostic message if chmod could not modify the
mode for file.
-h If the file is a symbolic link, change the mode of the link
itself rather than the file that the link points to.
-v Verbose, show filenames as the mode is modified*

The owner and group operands are both optional; however, at least one
must be specified. If the group operand is specified, it must be preceded by a colon (:)

* The -v option is non-standard and its use in scripts is not recommended.

The ownership of a file can only be altered by a super-user
for obvious security reasons.

Notes

Previous versions of the chown utility used the dot (.)
character to distinguish the group name. This has been changed to be a colon
(:) character so that user and group names can contain the dot character.

The -v option is non-standard and its use in scripts is
not recommended.

The owner/group can be either a numeric ID or a name. If a user/group name is also a numeric user ID, the operand is used as a user name.

chown exits 0 on success, and >0 if an error occurs.

Examples

Assign Ursula as the owner of "MyFile.txt" file in the Shared directory.

$ sudo chown Ursula /Users/Shared/MyFile.txt

Assign Ursula as the owner, and staff as the group for everything in the "tmp"
folder

$ sudo chown -R Ursula:staff /Users/Shared/tmp/

Reset the permissions on the entire home folder for the currently logged in user ($USER) this will reset the user ID number (UID) for all files. POSIX file permissions only use the UID, not the UserName or GUID.

$ sudo chown -R $USER ~$USER

“I never, ever say “I can't" about anything. I might say “I don't have the authority to make that decision” or “Building A is too heavy for me to lift” or "I will need training before I pilot that space shuttle” - Mike Huber